A gas turbine engine includes a fan section that drives air along a bypass flowpath. The fan section includes a fan rotor that includes a plurality of slots. A fan blade includes a root and a blade. Each of the plurality of slots is sized and shaped to receive the root of one of the fan blades.
A base of the root of the fan blade includes a front surface and a rear surface that are substantially flat and flush with a face of the fan rotor. The root also includes two side surfaces, which can be straight or curved. The front surface, the rear surface, and the side surfaces are connected to a bottom surface. The intersection of each of the side surfaces with each of the front surface and the rear surface defines an edge.
A cross-sectional area of the root taken substantially parallel to the bottom surface defines a perimeter having four corners, each of the corners defining part of the edge. The edges where the side surfaces meet the front surface and the rear surface are high stress areas and can be subject to handling damage. If any damage occurs, the local concentrated stress can increase significantly.
Additionally, the root cannot be treated with aggressive surface treatments, such of deep-peening, low plasticity burnishing or laser shock peening, as the edges of the root could be deformed by these aggressive treatments.